Current interrupting means



,-July 5, 1938. E. o. sCHwElTzEmJR 2,122,872

CURRENT INTERRUPTING MEANS Fla/.0

Patented July 5, 1938 UNITED STATES PATENT OFFICE Claims.

My invention relates generally to circuit opening and closing devices and it has particular relation to such devices of the non-arcing type.

In the prior art considerable difficulty has been 5 experienced in arcs drawn between the contact members of circuit opening devices. Because of such arcing there is a tendency for the contact members to be burned, thereby causing pitting of the contact surfaces and consequently poor conl() tact conditions between the contact members. In many instances there is the danger that an inflammable gas may be ignited in the event that an arc occurs on the opening of Contact members. Many devices have been proposed for eX- tinguishing arcs when they are formed. HOW- ever, insofar as I am aware, no one has ever proposed to prevent the formation of the arc on the opening of Contact members by changing the conditions under which the contact members are opened or the final break in the circuit is effected.

In circuit opening devices of the metallic contact type, arcing is caused by the ionization of a portion of the surface of one or both of the contact members. The ionization is a function of the heat generated in the surface of the contact members by the current flowing therethrough at the time that they are separated. Since the specific heat of metal, particularly copper, is

relatively low, there is a rapid vaporization Of the metal in the contact surfaces of the contact members. The ionized particles form a conducting path between the contact members and it is this path which causes the arc to be sustained,

the path being of relatively low resistance.

The object of my invention, generally stated, is to provide a circuit opening device which shall be simple and efhcient in operation and which may be readily and economically manufactured and installed.

The principal object of my invention is to provide for breaking an electric circuit between two portions of a non-metallic conducting fluid.

Another important object of my invention is to provide for opening an electric circuit between quantities of non-metallic conducting liquid surrounding the contact members of a circuit breaking device.

Another object of my invention is to provide a conducting liquid container around each of the contact members of a circuit breaking device, together with means for relatively moving the contact members to open the circuit between the portions of the liquid in each container.

v Another object of my invention is to provide a circuit breaking device in which the main contact members are separated in a conducting liquid and the final break is effected between two portions of the conducting liquid.

Other objects of my invention will in part be 5 obvious and in part appear hereinafter.

Accordingly, my invention is disclosed in the embodiment hereof shown in the accompanying drawing and comprises the features of construction, combination of elements and arrangement 10 of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For more complete understanding of the na- 15 ture and scope of my invention, reference may be had to the following detail description, taken in connection with the accompanying drawing, in which:

Figures l, 2 and 3 are views, partly in side elef- 20 vation and partly in section, showing different operating positions of my novel circuit breaking device.

According to my invention I provide for eifecting the final break in a circuit opening device 25 between two portions of conducting liquid, preferably of a non-metallic type, rather than between two metallic contact surfaces or between a conducting liquid and a metallic member. When this manner of opening an electric circuit 30 is employed, I have found that there will be no ionized arc path set up by ionized particles as is the case when the circuit is broken between the metallic contact surfaces. The final break is effected entirely between two portions of a 35 conducting liquid.

In order to form and sustain an arc there must be a certain amount of thermionic emission from one of the contact members between which the arc is formed. When the contact mem- 40 bers are formed of a metal, such as copper, having a relatively low specific heat, there is a considerable amount of thermionic emission, as set forth hereinbefore, and therefore there. is a tendency for an arc to form and to be sustained. 45 For the same amount of heat energy involved, the rise in temperature of a non-metallic conducting liquid will be relatively small compared to the temperature rise of the metallic contact member. There is, therefore, no tendency for 50 an arc to form or to be sustained. In addition, because of the cooling eiect of the conducting liquid, a sufficiently hightemperature necessary to produce the ionized arc path is not reached.

Referring now particularly to Figure l of the- 55 drawing, the reference character I0 indicates a container having at the bottom thereof a fixed contact member II secured to the container by means of a bolt I2 forming a terminal connection thereto. A movable contact member I3 in the form of a rod of conducting material is provided, as illustrated, and is disposed to engage the fixed contact member I I. The contact member I3 may be moved into and out of engagement with the contact member I I by any suitable means, not shown.

It will be observed that a liquid I5 is disposed within the container I0 and that its level is above the point where the contact members II and I3 are in mutual engagement. The conducting liquid I5 may be any of several non-metallic kinds; for example, dilute solutions of sulphuric acid, hydrochloric acid, zinc sulphate or copper sulphate, may be employed. In certain instances also a common salt solution may be used. It will be noted that the circuit is completed not only between the contact members II and I3, but also that it is completed through the conducting liquid I5. However, due to the fact that the resistance of the circuit including the contact members II and I3 is relatively small as compared to the resistance of the conducting liquid I5, comparatively little of the current flows through the liquid.

In order to provide for opening the circuit through two portions of the conducting liquid I5, an auxiliary container I6, preferably composed of insulating material, is provided and rotatably mounted at I1 on the movable contact member I3. It will be observed that the bottom of the auxiliary container I6 is recessed at I8 and that a tipping member I9 is provided, the upper portion 20 of which is arranged to engage the recessed portion I8. The tipping member I9 is illustrated as being a continuation of the xed contact member I I. However, it will be understood that it may be mounted as a separate member on the container I0 or in any suitable manner so as to effect the tipping of the auxiliary container or bucket I6 when the contact member I3 is moved downwardly into the position shown in Figure l.

The sequence of operation is illustrated in Figures l, 2 and 3, in the order named, for opening of the circuit. As illustrated in Figure 1, the device is in the fully closed position and is adapted to carry current under operating conditions. The device is initiated in operation by moving the contact member I3 in an upward direction by any suitable means. As illustrate-d in Figure 2, the contact member I3 moves out of engagement with the fixed contact member II. As a result, the entire current flow is transferred to the conducting liquid I5. However, since the circuit is not as yet fully open, there will be no arcing between the contact members II and I3. It will also be observed that the auxiliary container or bucket I6 is turned slightly toward the horizontal position. When the auxiliary container or bucket I6 is in the full horizontal position it will be observed that it entirely surrounds the lower end of the contact member I3. In this position it will be understood that both of the contact members II and I3 are individually surrounded by a container filled with conducting liquid and that the circuit is completed from the f xed contact member through the conducting liquid in the container I0, thence through the conducting liquid in the auxiliary container or bucket I5 to the movable contact member I3.

The continued upward movement of the movable contact member I3 lifts the auxiliary container or bucket I6 wholly out oi engagement with the remaining liquid in the container ID. Due to the fact that there is no metal-to-metal break, or metal to liquid break, there will be no ionized path created between the contact members. The nal break of the circuit will take place entirely between two portions of the conducting liquid I5. From tests which I have made on a circuit breaking device constructed in accordance with my invention, I have found that I can open an electric circuit without the formation of arcs which normally are formed when a like circuit is opened between metallic contact members.

Since certain further changes may be made in the foregoing construction and different ernbodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matters shown in the accompanying drawing or set forth in the foregoing description shall be interpreted as illustrative, and not in a limiting sense.

What I claim is:-

1. An electrical circuit breaking device comprising, in combination, a non-metallic conducting iiuid, separable contact means disposed in contact engagement under the surface of said fluid for carrying the main portion of the current of the circuit and disposed on separation thereof to permit the entire flow of current through said fluid, and means for subsequently interrupting the current flow through said fluid between two portions thereof.

2. An electrical circuit breaking device comprising, in combination, a main container, a conducting liquid in said container, a fixed contact member disposed in said container, a movable contact member disposed to engage said iixed contact member underneath the surface of said liquid to carry the main portion of the current of the circuit and on separation to permit the entire flow of current through said liquid, an auxiliary container composed of insulating material and rotatably mounted on said movable contact member and disposed to surround the lower end thereof, and a tipping member mounted on said main container and disposed to tip said auxiliary container as said movable contact member approaches said fixed contact member to permit engagement of said contact members, said auxiliary container being disposed to rotate on withdrawal of said movable contact member from engagement with said contact member to carry therewith a portion of said conducting liquid whereby the circuit is opened between the liquid remaining in said main container and the liquid f in said auxiliary container.

3. An electrical circuit breaking device comprising, in combination, an ionizable conducting liquid, separable contact means in contact engagement under the surface of said liquid for carrying the main portion of the current of the circuit and on disengagement thereof permitting the entire flow of current through said liquid, and means for subsequently interrupting the current flow through said liquid between two portions thereof and providing an air gap in the circuit.

4. An electrical circuit breaking device comprising, in combination, a conducting liquid which comprises water and a material dissolved therein providing a source of ions, separable contact means in contact engagement under the surface of said liquid for carrying the main portion of the current of the circuit and on disengagement thereof permitting the entire flow of current through said liquid, and means for subsequently interrupting the current flow through said liquid between two portions thereof and providing an air gap in the circuit.

5. An electrical circuit breaking device compricing, in combination, a conducting liquid comliquid for carrying the main portion of the current of the circuit and on disengagement thereof permitting the entire ow of current through said liquid, and means for subsequently inter rupting the current ow through said liquid between two portions thereof and providing an air gap in the circuit.

EDMUND O. SCHWEITZER, JR. 

